Biology

The correct answer is: B.Allopatric

Explanation:

When a new river forms and splits two populations, causing them to be geographically isolated from each other, it leads to allopatric speciation. In this case, the populations are separated by a physical barrier (the river), preventing gene flow between them. Over time, genetic differences can accumulate due to mutations, genetic drift, or natural selection, eventually leading to the formation of new species.

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